Infections of Hepatitis B virus (HBV) exist at epidemic levels worldwide. Following an incubation period of from about two to six months during which the host is unaware of the infection, HBV can lead to acute hepatitis and liver damage that cause abdominal pain, elevated blood levels of certain enzymes, and jaundice. It may also cause fulminant hepatitis, a rapidly progressive and often fatal form of the disease in which massive sections of the liver are destroyed.
Patients generally recover from acute hepatitis. However, some patients experience a persistence of high levels of viral antigen in their blood for an extended, indefinite period of time that results in a chronic infection. Such chronic infections lead to chronic persistent hepatitis, which is most commonly found in developing countries. By mid-1991, there were approximately 225 million chronic HBV carriers in Asia alone, and nearly 300 million carriers worldwide. Chronic persistent hepatitis is characterized by any one or more of the following symptoms: fatigue, cirrhosis of the liver, and hepatocellular carcinoma, a primary liver cancer.
In western, industrialized countries, groups at high risk for HBV infection include those in contact with HBV carriers or their blood samples. The epidemiology of HBV is similar to that of acquired immune deficiency syndrome (AIDS), which accounts for the common finding of HBV infection in patients with AIDS or AIDS-related complex. However, HBV is more contagious than HIV.
Within the past few years, vaccines have been produced successfully through genetic engineering. These vaccines are used widely, but cannot help those already infected with HBV. Daily treatments with genetically produced α-interferon also show promise, but are successful in only about one-third of the patients who receive it. Another drawback to the use of interferon is that it cannot be given orally.
A number of synthetic nucleosides have been identified that exhibit activity against HBV. The (−)-enantiomer of BCH-189 (2′,3′-dideoxy-3′-thiacytidine), known as 3TC, has been approved for the treatment of hepatitis B. See U.S. Pat. No. 5,532,246 as well as EPA 0 494 119 A1 filed by BioChem Pharma, Inc.
Adefovir (9-{2-(phosphonomethoxy)ethyl}adenine, also referred to as PMEA or ({2-(6-amino-9H-purin-9-yl)ethoxy}methylphosphonic acid), also has been approved in the United States for the treatment of patients infected with hepatitis B virus. See, for example, U.S. Pat. Nos. 5,641,763 and 5,142,051. Resistance to adefovir treatment in patients with HBV has been noted.
β-2-Hydroxymethyl-5-(5-fluorocytosin-1-yl)-1,3-oxathiolane (“FTC”), claimed in U.S. Pat. Nos. 5,814,639; 5,914,331 and 6,703,396 to Liotta et al., exhibits activity against HBV. See Furman et al., “The Anti-Hepatitis B Virus Activities, Cytotoxicities, and Anabolic Profiles of the (−) and (+) Enantiomers of cis-5-Fluoro-1-{2-(Hydroxymethyl)-1,3-oxathiolane-5-yl}-Cytosine” Antimicrobial Agents and Chemotherapy, December 1992, 2686-2692; and Cheng, et al., Journal of Biological Chemistry, 1992, 267 (20), 13938-13942.
U.S. Pat. Nos. 5,565,438, 5,567,688 and 5,587,362 (Chu, et al.) disclose the use of 2′-fluoro-5-methyl-β-L-arabinofuranolyluridine (L-FMAU) for the treatment of hepatitis B and Epstein Barr virus.
Yale University and The University of Georgia Research Foundation, Inc. disclose the use of L-FDDC (5-fluoro-3′-thia-2′,3′-dideoxycytidine) for the treatment of hepatitis B virus in WO 92/18517.
WO 96/40164 filed by Emory University, UAB Research Foundation, and the Centre National de la Recherche Scientifique (CNRS) discloses a number of β-L-2′,3′-dideoxynucleosides for the treatment of hepatitis B.
WO 95/07287 also filed by Emory University, UAB Research Foundation, and the Centre National de la Recherche Scientifique (CNRS) discloses 2′- or 3′-deoxy and 2′,3′-dideoxy-β-L-pentofuranosyl nucleosides for the treatment of HIV infection.
WO96/13512 filed by Genencor International, Inc., and Lipitek, Inc., discloses the preparation of L-ribofuranosyl nucleosides as antitumor agents and virucides.
WO95/32984 discloses lipid esters of nucleoside monophosphates as immuno-suppresive drugs.
DE 4224737 discloses cytosine nucleosides and their pharmaceutical uses.
Idenix Pharmaceuticals, Ltd. discloses 2′-deoxy-β-L-erythropentofurano-nucleosides, and their use in the treatment of HBV in U.S. Pat. Nos. 6,395,716; 6,444,652; 6,566,344 and 6,539,837. See also WO 00/09531. A method for the treatment of hepatitis B infection in humans and other host animals is disclosed that includes administering an effective amount of a biologically active 2′-deoxy-β-L-erythro-pentofuranonucleoside (alternatively referred to as β-L-dN or a β-L-2′-dN) or a pharmaceutically acceptable salt, ester or prodrug thereof, including β-L-deoxyribothymidine (β-L-dT), β-L-deoxyribocytidine (β-L-dC), β-L-deoxyribouridine (β-L-dU), β-L-deoxyribo-guanosine (β-L-dG), β-L-deoxyriboadenosine (β-L-dA) and β-L-deoxyriboinosine (β-L-dI), administered either alone or in combination, optionally in a pharmaceutically acceptable carrier. 5′ and N4 (cytidine) or N6 (adenosine) acylated or alkylated derivatives of the active compound, or the 5′-phospholipid or 5′-ether lipids were also disclosed.
von Janta-Lipinski et al. J. Med. Chem., 1998, 41 (12), 2040-2046 disclose the use of the L-enantiomers of 3′-fluoro-modified β-2′-deoxyribonucleoside 5′-triphosphates for the inhibition of hepatitis B polymerases. Specifically, the 5′-triphosphates of 3′-deoxy-3′-fluoro-β-L-thymidine (β-L-FTTP), 2′,3′-dideoxy-3′-fluoro-β-L-cytidine (β-L-FdCTP), and 2′,3′-dideoxy-3′-fluoro-β-L-5-methylcytidine (β-L-FMethCTP) were disclosed as effective inhibitors of HBV DNA polymerases. In addition, von Janta-Lipinski et al. discloses the biological activity of the triphosphate of β-L-thymidine (but not β-L-2′-dC) as a nucleoside inhibitor of endogenous DNA polymerases of HBV and DHBV. However, only triphosphorylated β-L-thymidine was evaluated, not the claimed unphosphorylated form, and there is no comment in the article on whether those β-L-nucleosides are phosphorylated in cells or in vivo or, more importantly, there is no comment on the efficacy of phosphorylation of β-L-thymidine in vivo. Because of this, the article does not teach that β-L-thymidine would have any hepatitis B activity in a cell or in vivo. See also WO 96/1204.
European Patent Application No. 0 352 248 A1 to Johansson et al. discloses the use of L-ribofuranosyl compounds for the treatment of hepatitis B.
Verri et al. disclose the use of 2′-deoxy-β-L-erythro-pentofuranonucleosides as antineoplastic agents and as anti-herpetic agents (Mol. Pharmacol. (1997), 51(1), 132-138 and Biochem. J. (1997), 328(1), 317-20). Saneyoshi et al. demonstrate the use of 2′-deoxy-L-ribonucleosides as reverse transcriptase (I) inhibitors for the control of retroviruses and for the treatment of AIDS, Jpn. Kokai Tokkyo Koho JP06293645 (1994).
Giovanni et al. tested 2′-deoxy-β-L-erythro-pentofuranonucleosides against partially pseudorabies virus (PRV), Biochem. J. (1993), 294(2), 381-5.
Chemotherapeutic uses of 2′-deoxy-β-L-erythro-pentofuranonucleosides were studied by Tyrsted et al. (Biochim. Biophys. Acta (1968), 155(2), 619-22) and Bloch, et al. (J. Med. Chem. (1967), 10(5), 908-12).
Morris S. Zedeck et al. first disclosed β-L-dA for the inhibition of the synthesis of induced enzymes in Pseudomonas testosteroni, Mol. Phys. (1967), 3(4), 386-95.
In Addition, Cytosine Derivatives are useful as Intermediates for Production of Drugs such as Cytidine Diphoslphate Choline whose Generic Name is Citicoline.
Lin et al. “Synthesis of Several Pyrimidine L-Nucleoside Analogues as Potential Antiviral Agents” Tetrahedron, 1995, 51 (4), 1055-1068, discusses that β-L-5-iodo-2′-deoxyuridine (β-L-IUdR, compound 7) is active against herpes infection and various other DNA viruses, that BVdU and β-L-BV-ara-U are also active against herpes, β-L-BV-ara-U is active against varicella-zoster virus; and that 2′,3′-dideoxy-β-L-azacytidine was found to be active against HBV.
U.S. Patent Publication No. 20030083306 filed by Idenix Pharmaceuticals, Ltd. discloses 3′-prodrugs of 2′-deoxy-β-L-nucleosides for the treatment of HBV. See also WO 01/96353.
U.S. Pat. No. 4,957,924 to Beauchamp discloses various therapeutic esters of acyclovir.
In the Apr. 17-21, 2002 European Association for the Study of the Liver meeting in Madrid, Spain, Sühnel et al. of Gilead Sciences, Inc. presented a poster indicating that combinations of adefovir with β-L-2′deoxythymidine produce additive antiviral effects against HBV in vitro.
Treatments for hepatitis B infection are also described in Lok and McMahon, AASLD Practice Guidelines, pp. 1225-1241 (2001), including treatment with interferons. Eastern woodchucks chronically infected with the woodchuck hepatitis virus (WHV) were used as a model of HBV infection to study the antiviral effect of 1-(2-fluoro-5-methyl-β-L-arabinofuranosyl)-uracil (L-FMAU) and WHV surface antigen vaccine. The humoral and cellular immunity associated with the combination of L-FMAU and vaccine resembled that observed in self-limited WHV infection. Menne et al., J. Virology, 76(11):5305-5314 (2002).